I thought random encounters was created then you enter an cell, however yesterday I exited an cave went around an corner and into two bandits who killed me.
Went back to the auto save after I exited the cave and this time it was an farmer who I killed because I thought he was an bandit curious I tried again and got two hunters.

Wonder if the auto save is done before you actually exit the cave so the utside is populated on load. However autosave saves inside shops as reloading does not change their inventory.

Shop inventory is set when you enter AFAIK. Autosave is done at the start of the action which triggers it: atuosave first, action second. So yes, if you leave a shop, the autosave is you still inside. As should be obvious when you reload that autosave. Similarly, if you autosave on rest, the time shows the start of the rest period.